The impressive part is that Gates is a self-made billionaire. From being a teenager interested in writing computer programs to piloting a multi-billion-dollar company, Gates’ success story has served as an inspiration for many.

The even more impressive part is that Gates has put his massive net worth to good use. He and his wife started the Bill & Melinda Gates Foundation, through which they have given away more than $28.0 billion.

Bill Gates’ Net Worth is $82.9 Billion

As you would imagine, Gates became interested in computer software at a young age. He wrote his first computer program using his school’s “Teletype Model 33” ASR terminal on a General Electric Company computer.

The computer prodigy enrolled at Harvard College in the autumn of 1973. A year later, he saw the release of the “MITS Altair 8800” microcomputer (not very “micro” by today’s standards) and believed that it would be a great opportunity to start a computer software company. So he dropped out of Harvard and with his childhood friend Paul Allen, Gates started Microsoft. The rest is history.

When Bill Gates started Microsoft, he knew that computer manufacturers really needed computer programs to sell to users, so he started writing them. In 1980, Microsoft created the “MS DOS” operating system for International Business Machines Corp. (NYSE:IBM). One year later, Microsoft was generating $16.0 million in revenue.

The company introduced the first retail version of Microsoft “Windows,” “Windows 1.0,” on November 20, 1985. Since then, subsequent versions of the operating system have been adopted by almost every home and office in the world.

To give you an idea of just how successful Microsoft’s products have become, here are some numbers:

From 1985 to 1990, Microsoft sold less than two million copies of all versions of Windows OS. As more people started embracing personal computers, sales picked up. (Source: “A Brief History of Windows Sales Figures, 1985-Present”, TIME, May 7, 2013.) Four million copies were sold in the first year that “Window’s 3.0” was released. In the first year of the launch of “Windows 95,” 40 million copies were sold.

Fast-forward to the 21st century, Windows is still the most popular choice among PC users. “Windows 7” sold 100 million copies within the first six months of its release and so did “Windows 8.” By January 2016, “Windows 10” is on more than 200 million monthly active devices. (Source: “Windows 10 Now Active on Over 200 Million Devices,” Windows Blog, January 4, 2016.)

Today, Microsoft is one of the largest companies in the world. With a market cap of over $400 billion, the company is only behind Apple Inc. (NASDAQ:AAPL) and Alphabet Inc (NASDAQ:GOOG). In Microsoft’s 2015 fiscal year, the company generated $93.6 billion in revenue and $18.2 billion in operating income. (Source: “Earnings Release FY15 Q4,” Microsoft Corporation, July 21, 2015.)

While Bill Gates’ stake in Microsoft stock helped him build a net worth of astronomical scales, Gates has also invested in other companies. Through his investment firm Cascade Investment L.L.C., Gates holds interests in a variety of companies, including McDonald’s Corporation (NYSE:MCD), Ecolab Inc. (NYSE:ECL), and Warren Buffett’s Berkshire Hathaway Inc. (NYSE:BRK.A).

After creating one of the most dominant tech giants in the world, Bill Gates decided to put his impressive net worth to good use. Inspired by the philanthropic work of Andrew Carnegie and John D. Rockefeller, Gates and his wife established the William H. Gates Foundation in 1994. The couple then combined several family foundations to form the Bill & Melinda Gates Foundation in 2000. Today, it is the largest private foundation in the world.

The foundation works both in the U.S. and around the world, tackling issues in areas such as health and education. The couple’s efforts have started a wave of charitable activities among the billionaires. Notably, legendary investor Warren Buffett has donated more than $21.5 billion to the Bill and Melinda Gates Foundation. (Source: “Warren Buffett Makes $2.84 Billion Donation to Gates Foundation and Charities,” The Guardian, July 7, 2015.)